The crust and uppermost mantle s-wave velocity structure beneath japan islands revealed by joint analysis of p-and s-wave receiver functions

We have studied the crust and uppermost mantle S-wave velocity structure beneath Japan Islands by using the teleseismic waveform data above Mw 6.0 recorded from January 2006 to February 2017 by 15 Hi-Net stations and the joint inversion technique of P- and S-wave receiver functions based on the Bayes theory. The results show that, beneath Japan Islands, the crust appear the characteristic of thinner in the south and east, and thicker in the north and west. The thinnest and thickest crust in the study region locate at station JSD (26km) and JGF(44km), respectively. The horizontal distribution of S-wave velocity in the study region are relatively complicated within upper and middle crust depth, while from the lower crust to the uppermost mantle depth, the velocity distribution is relatively uniform. The large earthquakes (above Mw 6.0) mainly took place at the edge of the high and low velocity zones.